HOPE FOR REVERSING DAMAGE FROM DRUGS

Even in low doses and even for a relatively short time, amphetamine use
leads to diminished capacity to learn in monkeys, a Yale study has found.

But in some cases the damage was reversed. And the treatment the
researchers used may hold promise for disorders linked to excessive levels
of the brain chemical dopamine.

Dr. Stacy Castner, the researcher at Yale who conducted the study, said the
team was surprised at the depth and persistence of the cognitive deficits
that resulted from six weeks' intermittent exposure to the drugs. A task
that undrugged monkeys were able to learn in fewer than 100 attempts was
beyond the ability of the drugged monkeys after up to 18 months of trials,
she wrote.

The implication for humans, she said, is that even brief periods of
dabbling in amphetamines could diminish the mind's performance for years
and perhaps permanently.

In the second phase of the study, the drugged monkeys were given an
experimental medication that stimulated a dopamine receptor, reducing the
dopamine's effect.

Dr. Patricia Goldman-Rakic, a neuroscience professor at Yale who supervised
the work, said that in some cases this succeeded in reversing the cognitive
damage, apparently permanently.

"The message from this research," she said, "shouldn't be that it's now
O.K. to take speed because there's a drug that can reverse it." Instead,
the hope is that studies into medications that alter dopamine levels could
eventually lead to treatments for a wide range of conditions, including
schizophrenia and attention deficit disorder, in which that delicate
balance is involuntarily disrupted.

The study was presented in Miami last week at a conference of the Society
of Neuroscience.